U.S. patent application number 11/477031 was filed with the patent office on 2007-03-01 for layered vibratory material conditioning apparatus.
Invention is credited to Eric Johnson.
Application Number | 20070045158 11/477031 |
Document ID | / |
Family ID | 37802539 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070045158 |
Kind Code |
A1 |
Johnson; Eric |
March 1, 2007 |
Layered vibratory material conditioning apparatus
Abstract
A vibratory conditioner includes a plurality of screens having a
planar surface through which there is a material feed opening,
wherein each screen is retained in vertical alignment such that all
planar surfaces are parallel, a chamber within which the parallel
screens are retained, means for conditioning air within the chamber
to a predetermined temperature and a predetermined humidity level,
and a vibratory generator operable to vibrate the chamber and
fluidize particles of material retained on a top surface of each
screen and to move the fluidized particles in a first
direction.
Inventors: |
Johnson; Eric; (Edgewood,
KY) |
Correspondence
Address: |
CARTER J. WHITE LEGAL DEPARTMENT;M-I L.L.C.
5950 NORTH COURSE DRIVE
HOUSTON
TX
77072
US
|
Family ID: |
37802539 |
Appl. No.: |
11/477031 |
Filed: |
June 28, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60694536 |
Jun 28, 2005 |
|
|
|
Current U.S.
Class: |
209/11 |
Current CPC
Class: |
B07B 1/58 20130101; B07B
1/48 20130101; B07B 13/16 20130101; B07B 1/46 20130101; B07B 1/38
20130101; B07B 1/06 20130101; F26B 17/007 20130101; F26B 17/006
20130101 |
Class at
Publication: |
209/011 |
International
Class: |
B03B 9/06 20060101
B03B009/06 |
Claims
1. A vibratory conditioner comprising: a plurality of screens
having a planar surface through which there is a material feed
opening, wherein each screen is retained in vertical alignment such
that all planar surfaces are parallel; a chamber within which the
parallel screens are retained; means for conditioning air within
the chamber to a predetermined temperature and a predetermined
humidity level; and a vibratory generator operable to vibrate the
chamber and fluidize particles of material retained on a top
surface of each screen and to move the fluidized particles in a
first direction.
2. The vibratory conditioner of claim 1, further comprising: means
for classifying material by size located on the top surface each of
the plurality of screens.
3. The vibratory conditioner of claim 2, further comprising: means
for humidifying air within the chamber to a predetermined humidity
level.
4. The vibratory conditioner of claim 1, wherein the means for
conditioning air within the chamber comprises: a heater operable to
heat the air within the chamber; a sensor to detect when the air
within the chamber has reached a predetermined temperature; a
controller operable to receive data from the sensor and to operate
the heater to maintain the predetermined temperature within the
chamber.
5. The vibratory conditioner of claim 4, wherein the means for
conditioning air within the chamber further comprises: a humidifier
operable to add moisture to the air within the chamber; wherein the
sensor can further detect when the air within the chamber has
reached a predetermined humidity level; and wherein the controller
is further operable to receive data from the sensor and operate the
humidifier to maintain the predetermined humidity level within the
chamber.
6. The vibratory conditioner of claim 5, further comprising: a
means for circulating the conditioned air within the chamber.
7. The vibratory conditioner of claim 6, wherein the means for
circulating the conditioned air within the chamber comprises: a
fan.
8. The vibratory conditioner of claim 1, wherein the means for
conditioning air within the chamber comprises: a chiller operable
to reduce the temperature of the air within the chamber; a sensor
to detect when the air within the chamber has reached a
predetermined temperature; a controller operable to receive data
from the sensor and to operate the chiller to maintain the
predetermined temperature within the chamber.
9. The vibratory conditioner of claim 8, wherein the means for
conditioning air within the chamber further comprises: a heater
operable to heat the air within the chamber; wherein the sensor
further detects when the air within the chamber has reached a
predetermined temperature; and wherein the controller is further
operable to receive data from the sensor and to operate the heater
to maintain the predetermined temperature within the chamber.
10. The vibratory conditioner of claim 9, further comprising: a
humidifier operable to add moisture to the air within the chamber;
a second sensor operable to detect when the air within the chamber
has reached a predetermined humidity level; and wherein the
controller is further operable to receive data from the sensor and
operate the humidifier to maintain the predetermined humidity level
within the chamber.
11. The vibratory conditioner of claim 1, wherein the material feed
opening of each screen is offset from the material feed opening of
adjacent screens.
12. The vibratory conditioner of claim 11, further comprising: a
cylindrical retainer holding each screen in fixed rotational
alignment relative to adjacent screens such that the material feed
opening in each porous element is an offset angle from the material
feed opening of each adjacent screen.
13. The vibratory conditioner of claim 1, further comprising: a
plurality of flow directors beneath the material feed opening of
each screen to direct material to a point on a lower screen such
that the material is directed around the screen before reaching the
material feed opening therein.
14. The vibratory conditioner of claim 1, wherein the vibratory
generator comprises: a reversible drive operable to fluidize
particles of material retained on the top surface of each screen in
a second direction within the chamber, wherein the second direction
is opposite the first direction.
15. An apparatus for conditioning and classifying material
comprising: a chamber; a plurality of screens retained within the
chamber, wherein each screen has a center orifice and an outer
edge, with a material feed opening radially extending through the
screen, wherein each porous element has a plurality of pores of a
unique predetermined pore size; a cylindrical connector affixed
within the center orifice of each of the plurality of screens,
wherein each connector interconnects with adjacent cylindrical
connectors to retain each screen in a fixed rotational alignment
such that the material feed opening through adjacent screens are
offset by a fixed offset angle; a vibratory generator operable to
vibrate the chamber and fluidize the material on each screen,
thereby causing it to move in a first direction; and means for
conditioning air within the chamber.
16. The apparatus of claim 15, wherein the screens are vertically
arranged such that particles greater than a desired maximum
particle size are retained on a top side of an uppermost
screen.
17. The apparatus of claim 16, further comprising: a spout in fluid
communication with the top side of the uppermost screen, wherein
the spout directs the particles greater than the desired maximum
particle size to an oversized particle collection area external to
the chamber.
18. The apparatus of claim 15, further comprising: an undersized
particle collection area located beneath a lowermost screen,
wherein particles having less than a desired minimum particle size
are collected in the undersized particle collection area.
19. The apparatus of claim 18, further comprising: a spout in fluid
communication with a top side of an uppermost screen, wherein
particles greater than a desired maximum particle size are retained
on the top side of the uppermost screen; and wherein the spout
directs the particles greater than the desired maximum particle
size to an oversized particle collection area external to the
chamber.
20. A method for conditioning and classifying particles comprising:
conditioning air in a chamber to a predetermined temperature and a
predetermined humidity level; circulating the conditioned air
within the chamber; dispensing a plurality of particles into the
chamber and onto a first of a plurality of vertically adjacent
screens, wherein each porous element has a plurality of pores of a
unique predetermined size and a radially extending material feed
opening, and wherein the material feed opening of adjacent screens
are offset from each other; vibrating the screens to separate
particles having a particle size greater than a desired minimum
particle size from particles having a particle size less than the
desired minimum particle size; directing the particles having a
particle size greater than the desired minimum particle size to
subsequent screens through the material feed opening in each porous
element; collecting the particles having a particle size less than
the desired minimum particle size at a bottom portion of the
chamber.
21. The method of claim 20, further comprising: collecting the
particles having a particle size greater than a desired maximum
particle size at a location external to the chamber
22. The method of claim 20, further comprising: dedusting the
particles prior to vibrating the screens.
23. The method of claim 22, further comprising: providing vertical
airflow to dedust the particles.
24. The method of claim 20, further comprising: dedusting the
particles while vibrating the screens.
Description
[0001] This application claims priority to Provisional Patent
Application Ser. No. 60/694,536 filed on Jun. 28, 2005 and
entitled, "Layered Vibratory Material Conditioning Apparatus"
incorporated herein by reference for all purposes.
BACKGROUND OF THE INVENTION
[0002] Many industries, such as pharmaceutical, food, plastic, and
waste, require material particles to be exposed to predetermined
conditions, such as heat or cold, as a part of an overall process.
Various types of equipment have been developed to integrate the
conditioning of particles with other production processes.
[0003] One such apparatus dries product as the product is gradually
moved across conveying surfaces towards the apparatus discharge.
The conveying surfaces are porous and enclosed within a vibrating
vessel. The vibrations fluidize the particles and cause them to
move forward through the apparatus. Air flow normal to the
direction of particle flow provides heated or cooled air through
the porous surface and the product. Such a single deck, rectangular
design requires many square feet of valuable production space.
[0004] Alternative designs have attempted to reduce the square
footage of production space required to condition material. One
such design uses a stack of non-vibrating, slowly rotating trays.
Material to be conditioned is dropped onto a top tray having
several slots providing fluid communication to a lower tray. As the
tray of material rotates within a conditioned chamber, a wiper
pushes material through one of the slots in the tray. The material
from the top tray then drops onto a second tray where the same
action is repeated. The material continues to be wiped into slots
on successive trays until it is released through a discharge spout
at the bottom of the apparatus. While this utilizes less square
footage than the first apparatus and provides longer exposure of
the material to the predetermined conditions, the trays do not
allow vertical air flow through the particles. Further, the trays
do not integrate material separation with conditioning.
[0005] It would be an improvement in the art to have a material
conditioner that uses minimal floor space. It would be a further
improvement in the art to have a material separator that could be
adapted to segregate oversized and/or undersized particles of
material as the material is being conditioned.
SUMMARY
[0006] In a first aspect of the invention, a vibratory conditioner
includes a plurality of screens having a planar surface through
which there is a material feed opening, wherein each screen is
retained in vertical alignment such that all planar surfaces are
parallel, a chamber within which the parallel screens are retained,
means for conditioning air within the chamber to a predetermined
temperature and a predetermined humidity level, and a vibratory
generator operable to vibrate the chamber and fluidize particles of
material retained on a top surface of each screen and to move the
fluidized particles in a first direction.
[0007] In another aspect of the invention, an apparatus for
conditioning and classifying material includes a plurality of
screens retained within the chamber, wherein each screen has a
center orifice and an outer edge, with a material feed opening
radially extending through the screen, wherein each porous element
has a plurality of pores of a unique predetermined pore size, a
cylindrical connector affixed within the center orifice of each of
the plurality of screens, wherein each connector interconnects with
adjacent cylindrical connectors to retain each screen in a fixed
rotational alignment such that the material feed opening through
adjacent screens are offset by a fixed offset angle, a vibratory
generator operable to vibrate the chamber and fluidize the material
on each screen, thereby causing it to move in a first direction,
and means for conditioning air within the chamber.
[0008] In another aspect of the invention, a method for
conditioning and classifying particles includes conditioning air in
a chamber to a predetermined temperature and a predetermined
humidity level, circulating the conditioned air within the chamber,
dispensing a plurality of particles into the chamber and onto a
first of a plurality of vertically adjacent screens, wherein each
porous element has a plurality of pores of a unique predetermined
size and a radially extending material feed opening, and wherein
the material feed opening of adjacent screens are offset from each
other, vibrating the screens to separate particles having a
particle size greater than a desired minimum particle size from
particles having a particle size less than the desired minimum
particle size, directing the particles having a particle size
greater than the desired minimum particle size to subsequent
screens through the material feed opening in each porous element,
collecting the particles having a particle size less than the
desired minimum particle size at a bottom portion of the
chamber.
[0009] Other aspects and advantages of the claimed subject matter
will be apparent from the following description and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a cutaway side view of a vibratory conditioning
apparatus.
[0011] FIG. 2 is a side view of the housing of the vibratory
conditioning apparatus.
[0012] FIG. 3 is a top view of a screen of the vibratory
conditioning apparatus.
[0013] FIG. 4 is a cross sectional view of a screen of the
vibratory conditioning apparatus.
[0014] FIG. 5 is a cross sectional detail of a screen frame
retained by the housing.
[0015] FIG. 6 is a perspective view of the screen stack.
[0016] FIGS. 7A and 7B depict flow paths in opposite
directions.
[0017] FIG. 8 is a cutaway side view of a vibratory conditioning
apparatus with overs removal.
[0018] FIG. 9 is cutaway side view of a vibratory conditioning
apparatus with low profile vibratory drives.
[0019] FIG. 10 is an embodiment of the vibratory conditioning
apparatus.
DETAILED DESCRIPTION
[0020] The claimed subject matter relates to an apparatus for
conditioning material. Referring to FIG. 1, the inventive vibratory
conditioner 100 includes a plurality of screens 110, a chamber 140,
a means for conditioning the air 160 within the chamber 140 to
predetermined parameters, and a vibratory generator 176. The
plurality of screens 110 are retained within the chamber 140. The
means for conditioning air 160 is operative to bring the
temperature and humidity levels within the chamber 140 to
predetermined levels. The chamber 140 is mounted to a base 154 in a
conventional manner by means of resilient members (not shown). The
vibratory generator 176, of conventional design, is securely
mounted within the housing floor 152 of the chamber 140 and is
operative to fluidize material on screens 110 within the chamber
140.
[0021] The chamber 140 is depicted in FIG. 2 and includes a
plurality of housing components 142, a cover 150, and a housing
floor 152. Referring to FIGS. 2 and 5, housing components 142
preferably are cylindrical defined by a housing wall 144 with an
outwardly protruding flange 146 around each of the upper edge 148
and the lower edge 149. As will be described, a screen 110 may be
retained between flanges 146 of two adjacent housing components
142. A clamp band 156 may be used around the outer periphery of the
adjacent flanges 146 to secure one housing component 142 to the
next with a screen 110 retained between them. By affixing several
housing components 142 together with a screen 110 retained between
housing components 142, a screen stack 102 is created (see FIG.
1).
[0022] The screen stack 102 may be formed from any number of
screens 110. In discussing the relationship of screens 110 within
the screen stack 102, it is understood that there is a top screen
104 and a bottom screen 106. It is further understood that in
discussing the relation of two screens 110 within the screen stack
102, there is an upper screen and a lower screen. For screens 110
located between the top screen 104 and the bottom screen 106, each
screen can be an upper screen and a lower screen, relative to the
next adjacent screen above or below, respectively.
[0023] Referring to FIGS. 1, 3 and 4, each screen 110 is planar and
has a plurality of pores 112 of a predetermined size. Material is
retained on a screen top surface 108. The pores 112 increase the
exposure of the material to the environmental conditions within the
chamber 140. The screens 110 are preferably round, but may be
square or rectangular to match the interior shape of chamber
140.
[0024] Referring to FIGS. 3, 4, and 5, screens 110 have an screen
periphery 114, at which there is a screen frame 116. As shown in
FIG. 5, screen frame 116 is retained between adjacent housing
components 142. Preferably, a gasket 158 is located between the
screen frame 116 and the housing component flanges 146 to seal the
interface.
[0025] A material feed opening 120 is present through each screen
110 and radially extends along a portion of the screen 110 for an
opening length 122. The material feed opening 120 has an opening
width 124 sufficient to allow material retained on screen top
surface 108 to pass through the upper screen 110 onto the lower
adjacent screen 110 or to a collection area 190 (shown in FIG.
1).
[0026] Referring to FIG. 6, the material feed opening 120 of each
screen 110 is offset from the material feed opening 120 of adjacent
screens 110. That is, the material feed opening 120 of each lower
screen 110 is positioned behind the material feed opening 120 of
the adjacent upper screen 110 relative to the flow direction 126 of
material around the screen 110. Thus, material dropping onto a
lower screen 110 from above must travel along the screen top
surface 108, around screen center 118, for a predetermined
distance. The offset angle 128 between material feed openings 120
of adjacent screens 110, as measured in the flow direction 126,
will be less than 360 degrees and should be more than 270 degrees
to ensure that the material has had adequate exposure to the
environmental conditions introduced into the chamber 140.
[0027] As shown in FIGS. 1, 3, and 4, each screen 110 has a center
orifice 130 through which a cylindrical retainer 132 is affixed.
The cylindrical retainers 132 provide a circular path for the
material to follow by blocking a path to the material feed opening
120 across the center of the screen 110. Also, stability to the
screen 110 is added by the cylindrical retainer 132 as a lower
retainer edge 134 of each cylindrical retainer 110 rests on an
upper retainer edge 136 of a lower adjacent cylindrical retainer
110. Further, the cylindrical retainers 132 hold each screen 110 in
a fixed rotational alignment, thereby preserving the offset angle
128 of each adjacent material feed opening 120. To maintain the
offset angle 128 of the material feed openings 120 of adjacent
screens 110, the cylindrical retainers 132 may include
castellations 138 positioned around the retainer upper edges 136
and retainer lower edges 134. The castellations 138 along the lower
retainer edge 134 of the cylindrical retainer 132 on an upper
screen 110 are held between the castellations 138 along the upper
retainer edge 136 of the cylindrical retainer 132 of the adjacent
lower screen 110. The castellations 138 ensure that no screen 110
rotates about a center axis 101 relative to the remaining screens
110 in the screen stack 102.
[0028] As shown in FIGS. 7a and 7b, a spiral baffle 184 may be
included on the one or more of the screens 110. The spiral baffle
184 creates a spiral path 186 extending from the screen center 118
to the screen periphery 114 (as shown in FIG. 7b) or from the
screen periphery 114 toward the screen center 118 (as shown in FIG.
7a). The fluidized material is directed by the spiral baffle 184
around the screen top surface 108 of the top screen 104, thereby
providing additional exposure to the conditioning provided by the
means for conditioning air 160. The material feed opening 120 may
extend across a portion of the spiral path 186 that is adjacent to
the screen periphery 114, as in FIG. 7b, or that is adjacent to the
screen center 118, as shown in FIG. 7a. Adjacent screens 110 may
include reversed paths 184 to maximize the exposure of the material
to the conditioning. For example, the screen 110 shown in FIG. 7b
may be the top screen 104, while the screen 110 shown in FIG. 7a is
below the top screen 104. Thus, material directed to the top screen
104 may be conveyed along path 186 to the material feed opening 120
adjacent to the screen periphery 114. The material dropped through
material feed opening 120 on the top screen 104 is then directed
along the path 186 of the second screen 110 from the screen
periphery 114 to the material feed opening 120 near the screen
center 118.
[0029] Referring to FIGS. 1, 2, and 8, the means for conditioning
air 160 within chamber 140 brings the air to a predetermined
temperature and humidity level. The predetermined temperature
and/or humidity level may be programmed by an operator. The means
for conditioning air 160 may include heating and/or cooling units,
humidifiers, and/or dehumidifiers. The means for conditioning air
160 may be retained at a location external to chamber 140 with
ducts 172 providing conditioned air to the chamber 140 via vents
164 through housing wall 144 or housing floor 152. An alternative
arrangement is shown in FIG. 9, in which a set of low profile dual
motors 176' are used to vibrate the chamber 140 rather than the
more typical vibratory drive associated with round separators as
shown in FIG. 1 as 176. By including a set of low profile dual
motors 176, a central air pipe 192 may be utilized to introduce
conditioned air to the chamber 140. This has the advantage of
providing a more uniform air flow within the chamber 140.
[0030] The means for conditioning air 160 within chamber 140 may
also include one or more sensors 166 and a controller 168. The
sensors 166 measure the air temperature and/or humidity level
within chamber 140. The controller 168 receives data from the
sensor 166 and operates components of the means for conditioning
air 160, such as a heater, cooling unit, humidifier, and/or
dehumidifier in response to collected measurements to maintain the
predetermined temperature and humidity level within the chamber 140
as measured by the sensor 166.
[0031] A means for circulating air 170 within chamber 140 may be
included to move conditioned air between and among screens 110,
subjecting material on each screen 110 to the desired air
temperature and humidity. The means for circulating air 170 may
include a fan or blower to force air from the means for
conditioning air 160 through one or more air ducts 162 and vents
164 through housing wall 144 and/or housing floor 152.
Alternatively, a vacuum may be used to pull conditioned air through
the chamber 140, thereby exposing particles to the conditioned
air.
[0032] The vibratory conditioner 100 may also include a means for
dedusting particles 174, wherein dust from the particles retained
on the top screen surfaces 108 is periodically removed. Means for
dedusting particles 174 may include a blower and vacuum system that
provides an air current through the chamber of sufficient strength
to separate fine particles that are adhered to more coarse
particles and evacuated the fine particles from the chamber 140.
Preferably, a vertical airflow is provided through the chamber 140
to dedust the particles therein. The same blower may be used to
dedust particles and to circulate air during processing of the
material. The airflow for dedusting particles may have a faster
velocity than the airflow for circulating conditioned air when the
same blower is used for both functions.
[0033] As previously stated, the vibratory generator 176 is
operable to fluidize material on the screens 110. The housing floor
152 of the chamber 140 securely mounts to the vibratory generator
176. The vibratory generator 140 imparts motion to the material on
each screen top surface 108 such that the individual particles of
material are fluidized and conveyed around the screen 110. The
fluidized material is led by the vibratory generator 176 such that
it spirals outward from the center axis 101 in a first direction.
As the particles reach the material feed opening 120, they are
gravity fed onto the lower sequential screen 110.
[0034] Referring to FIG. 10, the chamber 140 may be configured such
that a dedusting deck 194 is provided at the top of the chamber
140. After material is transferred onto the dedusting deck 194, the
dedusting process takes place and dust may be removed through a
dust removal spout 196. A cooling deck 198 may be provided beneath
the dedusting deck 194. The cooling deck 198 may include a spiral
baffle 200 to cool the product as it is transferred around the
screen of the cooling deck 198 to a center hole 202. An air inlet
206 directs conditioned air into the chamber 140 beneath the
cooling deck 198. A directing baffle 208 guides the conditioned air
from the air inlet 206 upward to flow through the cooling deck
screen 198. The conditioned material may then drop to a perforated
plate or screen 204 having a predetermined mesh size to separate
oversized material from the product being transferred through the
screen. The oversized material remains on the top surface of the
screen 204 until the vibratory motion imparted to the chamber 140
eventually causes the oversized material to be removed from the
chamber 140 through an overs spout 182'. The product, which has
been dedusted, conditioned and separated from oversized material
falls through the plate or screen 204 and may be removed through a
product outlet spout 210. A chamber floor 212 may be formed to have
an arced profile, such as that shown, to facilitate removal of the
product through the product outlet spout 210.
[0035] Returning to FIGS. 1, 2, and 8, the vibratory generator 176
may include a reversible drive system. The reversible drive system
provides a reverse flow direction to the particles on the screen
top surface 108. When the flow is reversed, particles still spiral
outward from the center axis 101, however the path is in a second
direction, opposite the first direction.
[0036] By varying the size of the pores 112 in subsequent screen
layers, sorting by particle size may also be accomplished as
material is conditioned. If classification of particles is
incorporated into the vibratory conditioner 100, through
appropriately sized pores 112, particles having a particle size
less than the pore size of the screen fall through the pores 112 to
the adjacent lower screen 110 or to the housing floor 152.
Likewise, particles having a particle size greater than the pore
size of the screen 110 are moved along the screen top surface 108
as the screen 110 is vibrated. The pore size of each screen 110 in
the screen stack 102 may be unique, wherein the pores 112 of each
screen 110 are of a different size than the pores 112 of other
screens 110 within the chamber 140.
[0037] In a first example, all screens 110 have a common pore size,
wherein each pore 112 is of a size sufficient to retain a particle
having a particle size equal to or greater than the smallest
acceptable particle size on the screen top surface 108 of the
screen 110. Particles having a particle size greater than the pore
size are retained on the screen top surface 108 of the top screen
104 until reaching the material feed opening 120. Material
deposited onto the second screen 110 is, likewise, retained on the
screen top surface 108 until reaching the material feed opening 120
of the second screen 110. In this manner, particles having a
particle size greater than the pore size of the screens 110
continue to be conditioned as they are transferred along the screen
top surface 108. Particles having a particle size less than the
smallest allowable particle size fall through successive screens
110 until reaching a collection area 190 on or near housing floor
152. The undersized particles are then segregated from the
particles having the desired particle size.
[0038] A modification of the first example would be to remove the
undersized material before beginning the conditioning process. This
may be accomplished by vibrating the chamber to remove the
undersized particles, that is, to dedust the acceptable particles.
After removing the undersized particles, conditioned air may be
introduced to the chamber and the vibratory direction modified to
convey acceptable material over the screen top surface 108 to the
material feed opening 120.
[0039] In a second example of simultaneous sorting and conditioning
of material, a top screen 104 has pores 112 of a size through which
particles having the maximum acceptable particle size may pass.
Thus, oversized particles are retained on the top screen 104 and
may be removed by a spout 182 or other removal system. Particles
having a particle size less than the maximum acceptable size pass
through the top screen 104 to the second screen 110. The second
screen 110 is sized to retain particles having an acceptable
particle size on the screen top surface 108 until the particles
have reached the material feed opening 120. Subsequent screens 110
in the screen stack 102 also maintain the particles having an
acceptable particle size on the screen top surface 108, thereby
providing additional exposure of the environmental conditions to
the acceptable particles.
[0040] The third example is a combination of the first two
examples. The top screen 104 may have pores 112 of a size
sufficient to retain oversized particles on the screen top surface
108. The oversized particles on the top screen 104 are removed.
Undersized particles and particles having a size within an
acceptable range pass through the pores 112 of the top screen 104
onto the second screen 110. All of the subsequent screens 110 may
have pores 112 of a size sufficient to permit the passage of
undersized particles. The undersized particles are collected in an
undersized particle collection area 190 on or near the housing
floor 152. Particles having a particle size within the acceptable
range are transferred along the screen top surface 08 of each
successive screen 110 until passing through the respective material
feed opening 120 to the next screen 110 or the finished product
collection area 190.
[0041] In a fourth example, wet material may be retained on a top
screen 104 and subjected to a drying environment in the chamber. As
the material dries, it may separate or shrink, depending upon the
material involved. After the material has separated into particles
of less than a predetermined size or after the material has reduced
in size to less than a predetermined size, the material can pass
through the top screen. Sequential screens may have decreasingly
smaller pore sizes, requiring additional drying time for material
to pass therethrough. In this manner, the level of dryness of a
particular material may be determined based upon the screen on
which the material is present at any time. The level of dryness
desired for a material and the particle size variation during the
drying process can be used to determine the number of sequential
screens required to sufficiently dry the material.
[0042] While the claimed subject matter has been described with
respect to a limited number of embodiments, those skilled in the
art, having benefit of this disclosure, will appreciate that other
embodiments can be devised which do not depart from the scope of
the claimed subject matter as disclosed herein. Accordingly, the
scope of the claimed subject matter should be limited only by the
attached claims.
* * * * *